<VV> Cold plug/ Hot coil= what?

[Frank DuVal]

No, you're Jeff, I'm Confused...

Anyway, the heat range of a spark plug is related to the ability of the 
plug to shed heat, typically by the heat conductive path from the tip to 
the shell. The longer this path, the harder it is to get rid of the heat 
from the tip of the plug.

A "hot" plug has a long path, therefore a hotter running tip 
temperature. This would be helpful if the engine ran cold in the 
combustion chamber, like a short trip city car running a rich mixture.

A "cold" plug has the short thermal path, therefore the tip runs cooler. 
This would be helpful for a hot running combustion chamber, say a lean 
mixture condition, high compression, extended trips at high speed, etc.

A plug that is too hot for its application will show damaged porcelian, 
typically really white and bubbly. The hot tip can also promote pinging.

To know if increasing the part number increases the temp of the plug you 
must consult the manufacturers literature. Not all manufacturers do it 
the same way.

Frank DuVal

Jeff Wilson wrote:

>Someone educate me what the 'temparuture' of a plug really means. 
>How does this relate to gap of the plug and 'hottness' of the spark, and 
>the voltage produced by the coil, etc etc? 
>
>I'm sooooo confused.... 
>
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